Report: Americans now spend an average of 6.3 hours per month on Facebook

The way people spend their time online is changing with the rise of social networking sites such as LinkedIn, Facebook, Tumblr and Twitter. That’s the latest from comScore, which just released a report indicating that Americans are spending more of their time on social networking sites.

In 2007, comScore found that social networking — whether that was the accepted term or not at the time — accounted for roughly one out of twelve minutes people spent online. Today, it represents one out of every six minutes.

That’s a truly amazing statistic, and much of it is due to the rise of Facebook. ComScore says that the Mark Zuckerberg-led company is now the fourth largest Internet property in the U.S., with 157 million monthly visitors. ComScore notes:

While other reports have been circulating that Facebook witnessed a pronounced user decline this month, comScore data shows quite a different story. Given that Facebook now reaches 73% of the total U.S. Internet population each month, one thing we should anticipate is that the site’s audience cannot grow forever.

Interestingly, comScore found that Facebook users on average spent 6.3 hours on the site each month. That’s up from 4.3 hours for the same period last year. Obviously, once Facebook captures most of the U.S. market it will need to grow its international presence and deepen the engagement among users, something that the latest statistics from comScore seem to indicate it is doing.

Eric Eldon at Inside Facebook has a good breakdown on how each of the measurement firms is tracking Facebook’s traffic. Check it out here.

Meanwhile, in the chart below, you can see that Facebook’s growth comes (in part) at the expense of MySpace.

John Cook is GeekWire's co-founder and editor, a veteran reporter and the longest-serving journalist on the Pacific Northwest tech startup beat. Follow him @johnhcook and email john@geekwire.com.